Trigger-operated electric switch mechanism



Dec. 6, 1966 D. W. JOHNSON TRIGGER-OPERATED ELECTRIC SWITCH MECHANISM Filed Nov. 20, 1964 2 Sheets-Sheet 1 INVENTOR. Dav/d M/ J0/7fl50/7 BY h/s af/omeys and Dec. 6, 1966 D. w. JOHNSON TRIGGER-OPERATED ELECTRIC SWITCH MECHANISM Filed Nov. 20, 1964 2 Sheets-Sheet 2 U mw H h E V0 WJS WW m Z M W .5 Y B /v 6 F United States Patent 3,290,463 TRIGGER-GPERATED ELECTRIC SWITCH MECHANISM David W. Johnson, Newington, Conm, asslgnor to The Arrow-Hart & Hegeman Electric Company, Hartford, Conn, a corporation of Connecticut Filed Nov. 20, 1964, Ser. No. 412,646 2 Claims. (Cl. 200-67) This invention relates to electric switches and, more particularly, to trigger-operated switches such as are commonly used in portable tools.

In some uses of switches here and abroad, it is desirable or necessary to have and maintain certain spacings of contacts and current-carrying parts to meet underwriters requirements and for safety reasons.

It is also desirable to have the circuit broken in two lines on each side of the motor or other device that is controlled and to have solid insulation between the contacts which were bridged.

It is desired also for the foregoing advantages to be achieved with a minimum number of parts which may be easily assembled and fabricated so that the overall cost of the switch and its assembly will be maintained at a minimum.

Therefore, it is an object of the invention to provide a novel switch arrangement which will provide the desired spacings of parts and through-type wiring utilizing a minimum number of economically fabricated parts so as to keep the costs of manufacturing and assembly within reasonable limits.

Another object of the invention is to provide a novel mounting of overcenter operating mechanism in such a switch.

Another object of the invention is to provide a novel means to hold the fixed contacts in proper position by utilizing the mounting of the overcenter mechanism.

Another object is to use the mounting of the overcenter mechanism as a guide for the movement of the movable contact carrier.

Other objects and advantages of the invention will become apparent as it is described in connection with the accompanying drawings.

In the drawings:

FIG. 1 is a side elevation view of a switch embodying the invention. a

FIG. 2 is a bottom view of the switch embodying the invention.

FIG. 3 is an interior elevation view of one-half of the casing when removed.

FIG. 4 is a view of the other half of the casing shown in elevation with the trigger operator, its supporting frame, movable contacts and supporting and positioning cradle in place.

FIG. 5 is a perspective view of the supporting and positioning cradle used in the invention.

FIG. 6 is a perspective view looking at the bottom of the movable contact carrier.

FIG. 7 is a detail view of one of the several terminal plates used in the invention.

FIG. 8 is a detail view of one of the several Contact plates used in the invention.

FIG. 9 is a detail view of the operating yoke used in the invention.

Referring to the drawings, the switch parts are housed within a molded insulating casing formed of two identical parts or halves (designated generally by 10 and 20) which are adapted to be placed face to face and secured together to contain all of the switch parts except the operating member and wire terminals.

The halves of the casing are hollowed out and recessed "ice appropriately to receive the various switch parts, as will appear as the invention is described below.

The first and second casing halves 10 and 20 are secured together by a U-shaped wire clip 12 which is adapted to seat within aligned grooves 10g and 20g formed in the bottom and partway up the side Walls of the casing halves. The casing halves are additionally held together by a stamped sheet metal frame member 14 comprising a plate portion running along the top of the casing halves and overlying their joint. Laterally extending from the top of the frame and bent downwardly to lay within T- shaped. recesses formed in the side walls of the casing halves are four extensions (two on each side) having T- shaped heads 14a so that when the extensions are bent into the T-shaped recesses, the frame is held from removal and the two parts of the casing are held together.

The frame also holds and guides a rectangular bar 16a of a trigger member 16, preferably formed of molded in sulating material having a longitudinal recess formed within one end in which is seated a coiled compression spring 15, one end of which presses against the trigger bar 16a while the other end presses against an extension 14e bent down from the end of the frame toward the casing.

For operating the switch mechanism Within the casing, as will hereinafter appear, the trigger bar 16a has a finger 16 formed thereon and extending inwardly of the casing to engage one end of an overcenter coiled compression spring 17, the other end of which seats on a central nub 1811 of a U-shaped stamped sheet metal switch operating yoke 18.

As the overcenter spring 17 is moved back and forth as the trigger 16 is pressed by the finger of the operator against the bias of the biasing spring 15, the operating yoke 18 will likewise move from the position shown in FIG. 4- counterclockwise in usual fashion with overcenter spring and yoke arrangements.

The yoke operates a movable contact carrier 30 of generally flat or plate-like form molded from insulating material. The contact carrier is slidable on the floor of the casing and has an aperture 32 for a finger 18] which extends from the transverse portion of the yoke opposite to the nub 18m. The margins of the aperture 32 nearest the ends of the contact carrier are inclined so that the aperture diverges (as may be been in FIG. 4) away from the side thereof through which the finger 18 enters. This allows movement of the finger within the aperture 32 as the switch operates.

Near each end the contact carrier 30 has a transverse slot formed in the surface thereof which faces the floor of the casing. In these slots are seated, edgewise, stamped sheet metal strips 34 and 37, respectively, whose ends are bent to lie along the edges of the carrier. The bent ends form contact surfaces 33, 35 and 36, 38.

To guide the movement of the contact carrier longitudinally and rectilinearly, a broad fiat rib 39 is formed on the inner surface of the contact carrier (the upper surface as viewed in FIG. 4) running longitudinally along the center of the carrier, being interrupted at the center of the carrier by aperture 32. Rib 39 is adapted to slide in a longitudinal, rectangular channel formed in the bottom or inner surface of a cradle 50 to be hereinafter described.

In each casing half are two spaced recesses or depressions formed to receive and fit two wire terminal members or plates like 40 in FIG. 7. Only two (41 and 42) are visible in the drawings (FIGS. 1 and 3). Each terminal plate has two lugs 43 extending from opposite parallel edges and lying in small recesses provided for them in the edges of said depressions. The plates are preferably stamped from sheet metal with central holes which are tapped and into which are threaded conventional binding screws 44. To provide access to these screws and terminal plates from the outside of the casing, the walls of the casing halves are apertured adjacent the terminal plates and screws.

Lying against the inner surface of each terminal is a fixed contact stamped from thin resilient sheet metal into the shape of FIG. 8. Only portions of three of these contacts are visible, namely 45, 46 and 48'. The bodies of the contacts lie against their wire terminals while legs 45' and 46' and 48' extending therefrom project along the sides of the casing into the paths of the movable contacts 33, 35, 36 and 38, respectively. Thus, the movable contact 37 will bridge fixed contact legs 45' and 48' and movable contact 34 will bridge contact 46' and its not visible counterpart.

In order:

(a) To hold the terminal plate and fixed contacts in place;

(b) To guide the movement of the movable contact carrier;

(c) To provide a bearing for the trunnions of the operating yoke, and

(d) To provide adequate spacing and insulation of the contacts and wire terminals,

a cradle member 50 of form shown in FIG. is provided. This cradle may be formed of molded insulating material in generally rectangular prismatic shape with two recesses 52 in each side to make room for the four shanks of the terminal screws 43. Also, a large central recess 54 or well, to accommodate the overcenter spring 17, yoke 18, trigger finger 16 and their movements is provided in the top or outermost face of the cradle.

To provide bearings for the yoke trunnions, transversely opposed semi-circular aligned notches 56 are provided in the top side walls of the large recesses 54. To locate the cradle vertically (referring to FIG. 4) in the casing, a transverse rib 58 is provided at each end of the cradle adjacent the edge nearest the movable contact carrier. The ribs slide or fit in complementary channel-s 22 formed therefor in the casing halves.

From the foregoing, it will be seen that the invention provides pairs of fixed contacts on opposite sides of the casing (such as 46, 48) which are adapted to be bridged by movable contacts (such as 37) as the trigger is moved by the operators finger against the bias of its biasing spring to cause overcenter operation of the overcenter spring 17 and consequent movement of the movable contact carrier 30. The invention provides for a break through both sides of the electric circuit whose lines may be fed through the switch, i.e. in one side and out the other. There is, thus, a double break in the circuit as the circuit is opened, causing less arcing and increased life of the switch. Moreover, solid insulation is provided to maintain the proper spacing of the current-carrying parts at proper values. The cradle, thus, performs a quadruple function as above outlined and, in addition, facilitates the assembly and, thus, reduces the cost of manufacture of the switch.

Modifications within the scope of the invention and additional advantages will occur to those skilled in the art. Thus, the invention is not limited to the precise form and configuration of the preferred embodiment herein described.

What is claimed is:

1. An electric switch comprising a casing having opposite side walls, switch contacts and wire terminals lying against said side walls, an operating member mounted on said casing and movable to and fro, an overcenter spring interconnected with and movable through an overcenter position by said operating member, a swingable yoke interconnected with and moved by said spring independent of said operating member as the operating member moves through said overcenter position, a cradle made of insulating material hollowed out to receive said spring and yoke, means on the cradle pivotally supporting the yoke, said cradle being positioned in said casing between said opposite casing walls and imposing a solid insulation barrier between opposite wire terminals, said cradle having its bottom face spaced from the bottom wall of said casing leaving a passage extending from wall to wall between said opposite side walls, a generally fiat insulating contact carrier slidable in said passage and guided by said cradle and bottom casing wall, bridging contacts carried by said carrier and extending across said passage and engaging said opposite switch contacts, said yoke engaging said carrier and moving it causing contact engagement and disengagement.

2. An electric switch as claimed in claim 1 wherein said casing has a contact and terminal receiving recess in each of its opposite side walls, said cradle extending across said casing and holding said terminals and contacts in their recesses.

References Cited by the Examiner UNITED STATES PATENTS 2,050,705 8/ 1936 Krieger. 2,120,423 6/1938 Bentley. 2,210,501 8/1940 Sachs 20076 ROBERT K. SCHAEFER, Primary Examiner.

KATHLEEN H. CLAFFY, Examiner.

D. SMITH, Assistant Examiner. 

1. AN ELECTRIC SWITCH COMPRISING A CASING HAVING OPPOSITE SIDE WALLS, SWITCH CONTACTS AND WIRE TERMINALS LYING AGAINST SAID SIDE WALLS, AN OPERATING MEMBER MOUNTED ON SAID CASING AND MOVABLE TO AND FRO, AN OVERCENTER SPRING INTERCONNECTED WITH AND MOVABLE THROUGH AN OVERCENTER POSITION BY SAID OPERATING MEMBER, A SWINGABLE YOKE INTERCONNECTED WITH AND MOVED BY SAID SPRING INDEPENDENT OF SAID OPERATING MEMBER AS THE OPERATING MEMBER MOVES THROUGH SAID OVERCENTER POSITION, A CRADLE MADE OF INSULATAING MATERIAL HOLLOWED OUT TO RECEIVE SAID SPRING AND YOKE, MEANS ON THE CRADLE PIVOTALLY SUPPORTING THE YOKE, SAID CRADLE BEING POSITIONED IN SAID CASING BETWEEN SAID OPPOSITE CASING WALLS AND IMPOSING A SOLID INSULATION BARRIER BETWEEN OPPOSITE WIRE TERMINALS SAID CRADLE HAVING ITS BOTTOM FACE SPACED FROM THE BOTTOM WALL OF SAID CASING LEAVING A PASSAGE EXTENDING FROM WALL TO WALL BETWEEN SAID OPPOSITAE SIDE WALLS A GENERALLY FLAT INSULATING CONTACT CARRIER SLIDABLE IN SAID PASSAGE AND GUIDED BY SAID CRADLE AND BOTTOM CASING WALL, BRIDGING CONTACTS CARRIED BY SAID CARRIER AND EXTENDING ACROSS SAID PASSAGE AND ENGAGING SAID OPPOSITE SWITCH CONTACTS, SAID YOKE ENGAGING SAID CARRIER AND MOVING IT CAUSING CONTACT ENGAGEMENT AND DISENGAGEMENT. 